Furnace for the direct reduction of metallic ores



June 2, 1925 A. J. F. J. COUSIN FURNACE FOR THE DIRECT REDUCTIN O1 METALLIC DRES Filed Maren 14. i923 Z171 ve n ta r;

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Patented June z, 1925.

UNITED STATES n 1,s'4n,2os PATENT oFFIcE.)

ARTHUR JULES FRANCOIS JOSEPH cousin, or 'Jimizrriifsuist-MEUSE,4 ammi, As- SIGNOR To SOCIT ANONYME JOHN coxEnILL, or slimme, 31Min,; oo!- PANY QF BELGIUM.

l IE'OB THE DIR-ECT REDUCTION AOil' METALLIC alipucanon mea laren 14, 192s. serial N0. 624,946.

To all 'whom it may concern.'

Be it known that I, ARTHUR JULES FnANoIs JOSEPH COUSIN, a subject of the King of the Belgiens, residing at Jemeppesur-Meuse,inthe Kingdom of Belgium, have invented Vcertain new and useful Improvements in Furnaces for the Direct Reduction of Metallic Orcs, of which the following is a specification.

" to be used in different industrial operations, principally for the direct production of iron starting from its ores, butl suitable also for the calcination, roasting or sintering of other ores, the manufacture of lime, the

burning '"of bricks, of clinker inorder to obtain cement, the agglomeration ofV powdered ores with or without previous briquetting, and finally all operations based on the heatin of materials which should not retain a highl temperature when issuing from the furnace.

The improved furnace has, in its general construction, all the arrangements common to 'furnaces of the type known as tunnel furnaces and the hearth is formed by platforms connected end to end and carried on a train of trucks. It is distinguished however essentially from other furnaces of the same type by the fact that itis divided along its length by means of dempers into different zones or chambers, thus providing in one and the same furnace, chambers each producing separate reactions and independ- '35 ent of each other withoutreciprocal action being able to interfere with the final result.

In carryin out the invention practically the furnace 1s provided with one or more burners or lines of burners, which burn under pressure, arranged in the arch of the furnace and controlled in different Ways so as to produce for example in a certain zone an oxidizing or neutral flame and in another zone a reducing effect.

p In the case where the reduction is effected by a 'reducing gas passing through the material to be treated, the platforms of the trucks formingthe hearth of the furnace are made double and leave between them an empt space of a certain heigl'it which is close in atl the sides by the walls of the furnacev in such a way as to furnish a passage for the Gases which pass through under the draft of5 the chimney, after hav- .the upper platforms or boxes with shown in Figure 2 forming a continuation..

of the part shown in Figure 1 and connected This invention relatesto afurnace adapted at the line A-A.

Figure 3 is a transverse section. The `furnace shown is inlt'ended to be heated Aby gas, either producer gas of low qual-v`v Aof masonry formin -a tunnel in whicha train of trucks 2, rawn along b a chain or any other equivalent traction evice nt shown) traveling alon a track 3, I runs through the furnace an presents in succession each of its elementsY (or trucks 2) to the action of the burners 4. These burners 4 as shown are sim ly iron pipes set in the arch or crown ofthe furnace. The `air to support combustion is supplied to them by a blower 5 which communicates a certain preure to them for example 'about 10 centimetres of water. In consequence of this pressure and the narrow section of the gas conduits the current of air and gas acuires a considerable velocity which shifts orward the point of combustion some distance in front of the gas outlets.

It follows therefore that the gas conduits are sucientl cooled bythe passage of the cold fuel an the air, the maximum temperature Of which is 350 C. and that therefore all cooling bv means of water can be dispensed with. e position also of the burners in the arch or crown of the furnace removes them from the flame and contributes towards keeping them at a comparatively lowtem erature. The burners direct their flames Vollliquely in a downward direction on to the surfacev of the material to be trealted. V

The furnace in provided at the truck inlet end with a door 6 and at the truck outlet end with a damper 7 through the adjustable.

air is drawn into the conduit 10 by the blower which forces it to the burners through the conduit 11.

The trucks 2 have, in the example shown a lower platform 12 provided with longitudinally extending fianges 13 (see Figure 3) which project downwards and dip into gutdered material to be treated as shown by the arrows 17, Athen through the perforations in the bottoms of the boxes 16 and lthen into the space 18 between the two series of platforms 12 and 16 and finally escape by the chimney 19. y

The furnace is divided along its length into different zones or chambers each having their own special function.

The first zone 20 comprised between the door 6 for the entrance of the trucks 2 and the combustionl chamber 21 (which may be of the multiple type shown in the drawing) is the rone of preparation. It is into this zone that the flue 19 leading to the chimney opens.

The second zone called the zone of com-- bustion or reaction, is composed of one or more chambers 21 into which the burners 4 penetrate,the flames from which are projected directly onto' the material to be treated.

A third zone or zone of cooling completes the furnace.. This zone extends between the last combustion chamber 21 and the damper y 7- and is divided into two sections 22 and 23 by dampers 24 and 25 the function of which is to isolate the section 22 thus cutting it off from the action of the blower 5;.

In the normal operation the Atrain of trucks 2 connected to each other occupies the whole length ofthe furnace. The thrust which causes one truck to enter the-furnace causes another to emerge from the opposite end thereof The furnace therefore always contains the same number of trucks. A damper 26, placed in the zone of preparation20 is adjusted in such a way as to always be as near as possible to the train of trucks and yet leave sufficient draught to prevent the creation of any pressure in the combustion zone 21, but at the same time avoiding any reduction of pressure below atmospheric ressure. 'Ihe function of this damper 26 1s therefore yto maintain as much as possible a null pressure in the combustionchamber'21. Under .these conditions it is possible to maint-ain in one and the same furnace oxidizing and reducing chambers without the two reactions interfering with each other.

The material carried by thetrucks therefore becomes gradually heated up by contact with the burnt gases which are inert and still hot which fill the zone of preparation 20, andthe material already at a high temperature is passed into the combustion chamber 21. j

According to the nature of the operations to be effected the first burner 4 or the first line of burners 4 can be regulated by acting on the regulating cocks or valves so as to give an oxidizing or a neutral flame. Afterwards, as the trucks continue to advance, the material is exposed to the second burner 4 (or line of burners) regulated for example i so as to obtain a reducingv effect by causlng theffuel employed (e. g., gas, oil or powdered coal) to be supplied with a supply of air to support combustion reduced to a minimum.

In the cooling zone 22, the material while still hot is in a neutral atmosphere, without any appreciable pressure and is subjected to the reaction of the materials in contact e. g., metallic oxides and carbon, which reaction takes place in consequence of'the elevation of the temperature. This reaction in the case of iron oxide is endothermic and causes rapid cooling down to a temperature at which no reaction can take place. At this moment the material may be passed into the second zone of cooling 23 where it gives up the remainder of its heat to the air to support combustion and which circulates in the direction of the arrows 9, that is to say, in the reverse direction to that in which the material travels. This latter when completely treated emerges finally through the door 7.

The separation of the cooling zone into two sections 22 and 23 is for the purpose of preventing certain disadvantages the chief one of which is the drawing in of flames or burnt gases by the blower 5 with as a consequence the blowing into the combustion chamber 21 of air laden with carbon dioxide; on the other hand in the case of a reduction of pressure below atmospheric pressure in the combustion chamber 21 the air could be drawn in too great volume which .might cause cooling of the fialne and a general disturbance in the working of the furnace.

These accidents cannot occur as long as the pressure in section 23 of the cooling zone remains null or thereabouts. This is obtained by the working of the two dampers 24 and 25 between which there is an opening 27 pierced in the arch or crown of the furnace. The two dampers 24 and 25 are always lowered as much as' possible so as to just touch the surface'of the trucks as they pass through. The closing thus obtained is not however hermetic and-the air can incase there is any pressure formed in the chamber 22 escape 'through the opening 27 thus bringing back the pressure to the 'limitswithin which its effect is not harmful.' The zone 22 is therefore a zone in which the same,

' atmosphere can be maintained asin thev combustion chamber. l .a

In practice the door 7 'through which the trucks` emerge is provided with a wicket (not shown) which acts asa damperand serves to regulate the size of the opening 8.

` This door may occupy the positions and II, position I correspondin to the closed position. Y In the raised position I I o f this door the air enters through the space comprised between the platforms 1-2 and 16 of the "trucks, and to reach the blower passes lthrough the material to be treated.

The invention is-obviously not limited to the details ofvconstruction of the furnace and of the trucks as above described; ThusV forexample the trucks having double plat- I pforms might be replaced by tru'cks'havingv single platforms if the material to be treated (a moist mixture of oxides |and carbonJ for example) were made up in an agglomerated form, the reduction not being affected by the passage of a gaseous reducing agent through the material but by intimateconta/ct with the solid reducing agent. In .this case use is-mlade of a single combustion chamber 21, the production of a reducing gas being. not. requlred. In the example shown the burners 4c each have an air supply pipe 2S and a supply pipe A29 for gas or other fuel. Each plpe 1s provided with a regulatingvalve 30 which allows the combustion to be conducted at will under the conditions desired. 4 i

What I claim is:

1.1111 a furnace of the madam-bea 'a tunnel, a movable hearth, means whereby the said hearthis run continuously through the 153 tunnel, a door-closing the :entrance .of the tunnel abovethe movable hearth, a damper extending transversally above the movable hearth, la preparation zone -A comprised. be-

tween the s aid door anddamper, a pair off 'dampers -extending transversally above the movable hearth', combustion zones com rised between the first damper and the sai pair the cooling zone.

'of dampers,"eachl of the said combustion `zones .comprising inclined burners', whereby the flames of the said burners'are projected directly towards vthe surface of the movable '3 hearth, adamper closing the'4 tunnel above the movable hearth, a cooling zone comprised between thepair of dempers and the closingdamper, and -a blower drawing air Afrom the said cooling zone and forcingsaid air to the burners.

2. In a furnace of the kindl described, a

tunnel; a movable hearth, means whereby: the said hearth is runcontinuouslythroug the tunnel, dampe'rs arranged transversally in the said tunnel above the movable'hearth,i whereby the tunnel is divided into a prepalration zone," combustion zones, reduction zones and a cooling zone, vburners arranged in the combustion land reduction zones, a g pair of dampers'separating the cooling zone l into two'sections and an opening in the roof of the furnace, between the said pair ofjdanr pers whereby a pressure only slightly above that of the atmosp combustion chamber and the 3. JIn 'a furnace of the kind described, a tunnel, f trucks circulating continuously vin the said tunnel, the said trucks having a "I5 u here 1s maintainedin the first section of 'lower platform and an upper platform, the A lowerplatform being `rovidedwith longianges, water-gutters tudinally extending in which the said flan es are dlpped, wherebysa hydraulicseal- 1s' formed, perforated 1 bottoms forming part of the upper platform.

of the trucks, dempers arranged transversally'- inthe tunnel-above theupper-plat- ,v 'formsof fthe trucks whereby the tunnel 1s divided into a'preparation zone, a combusinclined towards the` perforated V,bottoms of the upper platforms of the ltrucks andf a tionl zone,'a reduction zone and a cooling-V `zone, burners arranged l1n the combustion.I

and reduction zones, the sald burners being blower drawing air fromthe cooling zone 

